This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our studies concern two projects: (i) DNA replication and (ii) kinases involved in cell signaling. To ensure high processivity during DNA replication, the DNA polymerase binds to a DNA sliding clamp, a ring shaped molecule that encircles DNA. In turn, the sliding clamp is loaded onto the DNA by the clamp loader complex. Previously, we have solved the crystal structure of the yeast sliding clamp PCNA bound to the clamp loader RFC. We have now generated crystals of the PCNA-RFC complex bound to DNA that diffract to ~14 [unreadable] at beamline 8.3.1 at the Advanced Light Source, Berkeley. We have improved the quality of the crystals and expect to get better diffraction of these crystals that will allow us to solve the structure. EGFR is an receptor tyrosine kinase which plays important role in cell proliferation and differentiation. Mig6 is a negative regulator of the EGFR kinase. We have solved the structure of the EGFR kinase-Mig6 to ~3.5 [unreadable] resolution. In the electron density obtained, the kinase protein can be placed easily. In addition, clear electron density is present for the Mig6 peptide, but due to the low resolution it is difficult to assign the register of the peptide. Hence, we are aiming to collect a higher resolution dataset to unambiguously place the Mig6 peptide.